Air suspension control apparatus



Feb. 12, 1963 R; W- GRAHAM 7 AIR SUSPENSION CONTROL APPARATUS Filed March 4, 1959 IN VEN TOR.

BY @Jezzfiday T TORNE Y United States Patent 3,ii77,2i)d AER SUSPENdlUN CUNTRfiL APPARATUS Robert W. Graham, Plirrninghain, Mich assignor to Genral Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Mar. 4, i959, Ser. No. 797,221 Claims. (Cl. 137-=52) This invention relates to vehicle air suspension high pressure storage tanks and more particularly to control apparatus therefor.

In prior art air suspension systems in which the high pressure storage tank is equipped with an inlet mounted muffler assembly, it has been customary to locate a check valve in the pressure line at some point between the tank and the source of compressed air.

An object of the present invention is to provide a simpliiied and improved check valve and mufller assembly for air suspension high pressure storage tanks.

Another object is to provide a combined Inufiler and check valve assembly.

A further object is to provide a surge mufiler assembly for an air suspension high pressure storage tank which is constructed and arranged so as to prevent backflow of compressed air from the tank to the source of compressed air.

Still another object is to provide a device of the type described including a tightly wound coil spring arranged in surrounding relation with respect to a stationary inlet tube, the coil spring having a closure secured in the end thereof adapted to resiliently engage the end of the tube responsive to tension of the coil spring.

Yet another object is to provide a mufiler assembly comprising a fitting having an open ended tubular member secured therein, a coil spring attached to said fitting and surrounding said tubular member, and a resilient plug in the end of the spring normally engaging thc open end of the tubular member.

These and other objects, advantages and features or" the invention will become more fully apparent as reference is had to the accompanying specification and drawings wherein:

P16. 1 is an elevational View, partly in section and with parts broken away, illustrating a high pressure storage tank having disposed therein a surge mutiier assembly incorporating the invention;

FEG. 2 is a fragmentary partially sectioned view of a portion of the structure shown in FIG. 1, illustrating the relationship of parts during movement of air into the tank; and

FIG. 3 is a fragmentary view looking in the direction of arrows 3-3 of MG. 1.

Referring now to the drawings and particularly FIG. 1, the reference numeral 2 designates generally a high pressure storage tank of the type utilized in vehicle air suspension systems. Tank 2 includes an internally threaded inlet flange i which is adapted to receive an air inlet fitting 6 having an orifice 3 extending therethrough. It will be understood that fitting 6, in turn, is connected by suitable conduit means, not shown, to an engine driven air compressor, also not shown.

In accordance with the present invention, inner end 1.9 of fitting 6 is provided with a bore 12 in which is press fitted an elongated open ended rigid tubular member 14 which extends into tank 2. Axially adjacent bore 12, inner end of fitting 6 is provided with an internally threaded counterbore 16 which is adapted to threadably receive a plurality of coils at the outer end of a tightly wound coil spring element 18. Spring element 18 extends into tank 2 in concentric relation with tube 14, a distance somewhat greater than the length of the latter.

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A plurality of coils at the inner end of element 18 surroundingly engage a plug element 2t) which abuttingly engages the open inner end 22 of tube 14 when spring 18 is in its normal unexpanded condition. in pactice, the axial position of plug 20 in spring 18 is adjusted so that face 24 of plug 2% exerts a sufficient pressure on the end of tube 14 to provide an air tight seal at the juncture of tube 13 and the face 24 of plug 2%. In order to assure effectiveness of sealing engagement between plug 2%? and the end 22 or" tube 14, the face portion 24 of the former is preferably formed of resilient material such as rubber which is bonded to the main body of the plu Alternatively plug 2 may be formed entirely of rubber-like material.

In operation, the evice functions as follows. Con.- pressed air supplied by an engine driven compressor, not shown, enters the inlet orifice d of fitting 6, passes through tube 14 toward the inner end 22 thereof and exerts pressure on plug 28, causing the latter to unseat. As a result of the axial movement of plug 2% incident to unseating thereof, the individual coils of coil spring 18 are caused to separate slightly (as shown in exaggerated form in FIG. 2) thereby providing a continuous helical slit-like opening extending from the outer to the inner end of the sprin Air emerging from open end 22 of tube 14 is therefore constrained to pass through the slit-like opening before emerging into high pressure tank 2. Because of the pressure diffusion accomplished by the action spring 18, the component of pulsing causing resonance is filtered out. Upon cessation of operation of the engine driven air compressor, previously referred to, air pressure within tube 1 quickly diminishes, thereby permitting coil spring 1? to return to the position shown in FIG. 1 which automatically restores plug 2 9 to the position effecting sealing engagement wtih the outer end 22 of tube 14. As soon as plug 29 resul s sealing engagement with tube 14, super-atmospheric air contained in tank 2 is prevented trorn flowing back into the air compressor.

From the foregoing it will be seen that a simplified and improved mufller assembly has been provided. The construction not only functions effectively as a surge mufiier but in addition automatically operates as a check valve assembly during all periods in which the mother is dynamically inactive, thereby eliminating the necessity of a check valve assembly between the muffler and source of compressed air.

While but one embodiment of the invention has been shown and described, it will be apparent that other changes and modifications may be made therein. it is, therefore, to be understood that it is not intended to limit the invention to the embodiment shown, but only by the scope of the claims which follow.

I claim:

1. In a high pressure storage system of the type including a source of pressure and a storage tank, a rnufiler assembly for said tank comprising a coil spring having a plurality of normally axially abutting coils, an inlet fitting connected to one end of said spring, a plug element disposed in the other end of said spring, an imperforate open-ended rigid tube disposed concentrically within said spring and having one end rigidly connected in communicating relation with said inlet fitting, the other end of said tube terminating at a distance from said fitting sufficient to normally cause engagement with said plug whereby the latter acts as a check valve preventing backflow of air through said tube to said inlet fitting.

2. In a high pressure storage system of the type including a source of pressure and a storage tank, a storage tank rnuiiier assembly comprising a coil spring having a plurality of normally axially abutting coils, a fitting secured to said tank having an inlet aperture formed therein, means threadably connecting one end of said spring to said fitting, a plug element disposed in the other end of said spring, an imper'forate open-ended rigid tube Within said spring having one end rigidly connected to said fitting in communicating relation with said inlet aperture, the other end of said tube terminating at a distance from said fitting snr'licient to cause said plug to normally engage said other end whereby to provide a check valve preventing backflow of air through said tube to said inlet fitting.

3. In a high pressure storage system including a source of air pressure and a storage tank, a rnuflier assembly comprising a coil spring having a plurality of normally axially abutting coils, an inlet fitting secured to said tank and threadably engaging one end of said spring, means forming an inlet aperture in said fitting, a plug element disposed in the other end of said spring, an imperforate open-ended rigid tube Within said spring having one end rigidly connected to said fitting in communicating relation with said inlet aperture, the other end of said tube terminating at a distance from said fitting sufficient to cause abutting engagement with said plug whereby the latter acts as a check valve preventing backflow of air through said tube to said inlet fitting, the latent tension of said coil spring being calibrated to yield under predetermined inlet air pressure exerted on said plug allowing the air to enter the space between said tube and said coil spring and emerge into the tank through the helical slit-like passage occuring upon expansion of said spring.

4. The structure set forth in claim 3 wherein said plug includes resilient means adapted to perfect fluid-tight sealing engagement with said other end of said tube.

5. The structure set forth in claim 3 wherein said plug includes a rubber-like seat at the end adjacent said tube.

References Cited in the file of this patent UNITED STATES PATENTS 659,456 Smith Oct.'9, 1900 1,572,701 Allec Feb. 9, 1926 2,286,841 Smith June 16, 1942 2,375,498 Seymour May 8, 1945 2,603,188 McKay July 15, 1952 2,896,661 Becker July 28, 1959 FOREIGN PATENTS 20,266 Denmark June 21, 1915 

1. IN A HIGH PRESSURE STORAGE SYSTEM OF THE TYPE INCLUDING A SOURCE OF PRESSURE AND A STORAGE TANK, A MUFFLER ASSEMBLY FOR SAID TANK COMPRISING A COIL SPRING HAVING A PLURALITY OF NORMALLY AXIALLY ABUTTING COILS, AN INLET FITTING CONNECTED TO ONE END OF SAID SPRING, A PLUG ELEMENT DISPOSED IN THE OTHER END OF SAID SPRING, AN IMPERFORATE OPEN-ENDED RIGID TUBE DISPOSED CONCENTRICALLY WITHIN SAID SPRING AND HAVING ONE END RIGIDLY CONNECTED IN COMMUNICATING RELATION WITH SAID INLET FITTING, THE OTHER END OF SAID TUBE TERMINATING AT A DISTANCE FROM SAID FITTING SUFFICIENT TO NORMALLY CAUSE ENGAGEMENT WITH SAID PLUG WHEREBY THE LATTER ACTS AS A CHECK VALVE PREVENTING BACKFLOW OF AIR THROUGH SAID TUBE TO SAID INLET FITTING. 